PROJECT SUMMARY/ABSTRACT The goal of this study is to understand how the COVID-19 crisis, and related changes in caregiver distress and interactions with infants, affects infant language development over a 12- month period. We propose to gather repeated measures of survey and video-recorded interaction data from a subsample (n = 100) of SMALL Talk caregiver-infant dyads during one- year of the COVID-19 pandemic. SMALL Talk is actively recruiting and interviewing low-income caregiver-infant dyads in an urban area to study predictors of children's risk of developmental language disorder (DLD) by 54 months. DLD is particularly high among low-SES children (Norbury et al., 2016). However, there are equally important inequalities for DLD risk among low-SES children (Schwab & Lew-Williams, 2016), which may be further exacerbated by the COVID-19 pandemic. Through this supplemental project, we aim to assess, during one year of the COVID-19 pandemic: (1) COVID-19-related forms and frequency of stress and resource needs among low-income caregivers with infants; (2) caregiver-infant interactions with primary and secondary caregivers at multiple, short-term intervals; and (3) how COVID-19-related stressors, caregiver distress, and access to resources affect caregiver-infant interactions and infant language development. We will use remote smart-phone based technology to gather on- line survey data and video recordings of caregiver-infant interactions multiple times during this one-year period. Innovative aspects of this supplemental grant include collecting multiple caregiver-infant interactions, including secondary caregiver-infant interactions, and using smart- phone technology to conduct in-home assessments among vulnerable groups who are often left out of digital data collection studies, including COVID-19 studies (Lourenco & Tasimi, 2020). We will use multi-level random-effects models to assess associations among caregiver distress, features of caregiver-infant interactions (including language use and caregiving quality), and infant language development. We will share this information with key stakeholders to inform the development of programs and policies to meet immediate needs of low-income families with infants. We will also publish rapid, open-access research articles and policy briefs to share evidence of COVID-19-related instability and stress in low-income families and how they are affect caregiver-infant interactions and child language development in the short- and long-term.